Pouch cell

Abstract

The present invention relates to the field of battery cells, particularly to a pouch cell comprising a packaging seal, a heating element and a fault switch, wherein the fault switch will activate the heating element to generate heat to make the packaging seal delaminate when the inner space of the pouch cell reaches a predetermined pressure, such that the pouch cell vents. The mechanism and components of these venting concepts can be designed to be fully compatible with existing manufacturing methods and typical cell handling situations. The most favorable configuration has both vent device components outside the cell, with nothing passing through or even into the seal. Such a configuration has the advantage of having no impact on the seal integrity relative to a conventional pouch cell, is easy to manufacture, and has improved safety.

What is claimed is: 
     
       1. A pouch cell, comprising a packaging seal, a heating element and a fault switch, wherein the fault switch will activate the heating element to generate heat to make the packaging seal delaminate when the inner space of the pouch cell reaches a predetermined pressure, such that the pouch cell vents. 
     
     
       2. The pouch cell according to  claim 1 , wherein the heating element is disposed between the two layers of the packaging seal or on top of the packaging seal outside the pouch cell. 
     
     
       3. The pouch cell according to  claim 2 , wherein the heating element is disposed on top of the packaging seal at tab side. 
     
     
       4. The pouch cell according to  claim 2 , wherein the heating element is a NiChrome wire or a polyimide-film insulated flexible heater. 
     
     
       5. The pouch cell of  claim 1 , wherein the fault switch capable of activating the heating element is at least one of the following; a pressure switch, an electronic switch in a battery management system, or a temperature switch. 
     
     
       6. The pouch cell according to  claim 5 , wherein the heating element is a NiChrome wire or a polyimide-film insulated flexible heater. 
     
     
       7. The pouch cell according to  claim 1 , wherein the fault switch is a pressure switch, and the pressure switch, the heating element and two tabs of the pouch cell will be electronically connected to form a closed circuit such that the heating element will generate heat to make the packaging seal delaminate by shorting the pouch cell when the inner space of the pouch cell reaches a predetermined pressure. 
     
     
       8. The pouch cell according to  claim 7 , wherein the pressure switch comprises:
 a concave dimple formed into the side of the packaging seal, 
 a conductive material coated in the concave dimple, and 
 two conductive wires connected to the heating element and one tab of the pouch cell respectively and without contacting with each other at the concave dimple; wherein 
 when the inner space of the pouch cell reach a predetermined pressure, the concave dimple will be caused to invert outwards so that the conductive material coated in the concave dimple will contact with the conductive wire to bridge the circuit. 
 
     
     
       9. The pouch cell according to  claim 8 , wherein the heating element is a NiChrome wire or a Kapton heater. 
     
     
       10. The pouch cell according to  claim 8 , wherein the heating element is disposed between the two layers of the packaging seal or on top of the packaging seal outside the pouch cell. 
     
     
       11. The pouch cell according to  claim 7 , wherein the heating element is disposed between the two layers of the packaging seal or on top of the packaging seal outside the pouch cell. 
     
     
       12. The pouch cell according to  claim 7 , wherein the pressure switch comprises:
 a spring, and 
 two conductive wires, 
 wherein the spring is disposed between the two conductive wires, the two conductive wires are connected to the heating element and one tab of the pouch cell respectively and without contacting with each other at the spring; 
 when the inner space of the pouch cell reach a predetermined pressure, the spring will be fully compressed to close the circuit, and once the venting accomplished, the spring will push apart the two conductive wires. 
 
     
     
       13. The pouch cell according to  claim 12 , wherein the heating element is a NiChrome wire or a Kapton heater. 
     
     
       14. The pouch cell according to  claim 12 , wherein the heating element is disposed between the two layers of the packaging seal or on top of the packaging seal outside the pouch cell. 
     
     
       15. The pouch cell according to  claim 7 , wherein the pouch cell further comprises a cell frame in which is placed a pouch cell, and the pressure switch comprises:
 a void area presented between the outer edge of a cell cup and the inner edge of the packaging seal, 
 optional point seals applied at the void area, 
 a first conductive material disposed on the outside region of the void area, and 
 a second conductive material attached to the cell frame, 
 wherein the first conductive material is opposite to the second conductive material and there is a void space between them, the first conductive material is connected to the heating element, and the heating element and the second conductive material are connected to one of the tabs of the pouch cell respectively; 
 when the inner space of the pouch cell reach a predetermined pressure, the cell cup will balloon to make the first conductive material contact with the second conductive material to bridge the circuit; 
 once the venting accomplished, the circuit will open spontaneously by separating of the first conductive material and the second conductive material. 
 
     
     
       16. The pouch cell according to  claim 15 , wherein the pressure switch comprises point seals applied at the void area, when the inner space of the pouch cell reach a predetermined pressure, the cell cup will balloon to pull the point seals apart and make the first conductive material contact with the second conductive material to bridge the circuit. 
     
     
       17. The pouch cell according to  claim 15 , wherein the void area is a void area between the cell cup and the tab side seal. 
     
     
       18. The pouch cell according to  claim 7 , wherein the pouch cell further comprises a pressure device which will apply a pressure to the seal side of venting to reseal it once the venting accomplished and the circuit open. 
     
     
       19. The pouch cell according to  claim 1 , wherein the heating element is a NiChrome wire or a polyimide-film insulated flexible heater. 
     
     
       20. The pouch cell according to  claim 1 , wherein the pouch cell is a Li-ion pouch cell.